SIERRAVISTA — Up to 2,000 people living just outside the southeast edge of Sierra Vista have had their water contaminated by E. coli, the utility management company for the affected area announced Friday.

Customers of the Eastslope Water Company are advised to boil their water for at least a minute before drinking it, said Keith Dojaquez, vice president and operations manager for Southwestern Utility Management, Inc., a Tucson-based company that manages the affected area as well as dozens of other water companies across the state.

The motor to the contaminated well is out of service and needs to be repaired before the well can be flushed out, Dojaquez said. The contamination could last up to 10 days before it is completely cleared.

The boundaries of the affected area are Camino Principal to the north, Campobello Avenue to the east, Ramsey Road to the south and Highway 92 to the west.

Utility company personnel first noticed something was wrong with the water on Tuesday, when a routine monthly test for contamination from samples collected the day before, came back positive. A more targeted testing of the water occurred on Wednesday, and on Thursday the results indicating an E. coli contamination in the well were received.

Dojaquez said that crews were dispatched to the area to make contact with residents in person and advise them to boil their water or use bottled water until further notice.

A flyer distributed to residents reads “boiled or bottle[sic] water should be used for drinking, making ice, brushing teeth, washing dishes, and food preparation until further notice.”

It goes on to list common symptoms related to the exposure of E. coli, including diarrhea, nausea, cramps and headaches, adding that exposure to the bacteria is a particular health risk to infants, young children and those with compromised immunse systems.

The well in question is sealed, and as of Friday there was no clear understanding as to how the contamination occurred.

“We really don’t know. E. coli is usually from warm-blooded mammals,” Dojaquez said. When a system has leaks, that could lead to potential contamination, but it is not known if that is what happened here.

“We have a couple of speculations, but we don’t know for sure,” he said.

The flyer distributed to residents outlines other potential causes.

“Bacterial contamination can occur when increased run-off enters the drinking water source (for example, following heavy rains). It can also happen due to a break in the distribution system (pipes) or a failure in the water treatment process,” it reads.

The system is being chlorinated and flushed, with repeat samples taken throughout the water system and the well. Residents will be notified by the company when the samples indicate the bacteria has been cleared.